So it's official. A programmer named
Blanka was able to get past all of the EFI issues and has provided a
working solution to natively run Windows XP on an a Mac. The programmer can
now claim the $13,854 prize thanks to his video of the installation and
booting of Microsoft's ubiquitous OS on an Intel-based iMac. Winxponmac.com posted
this on its site:

Contest has been won - updates to
follow shortly. All further donations will go into an account to
sustain the open source project that will be launched with the
initial solution.

You can head on over to Engadget to see
a 7.7MB
video of Windows XP on a Mac.

For those of you unfamiliar with the contest, here were the rules for $13k prize:

Instructions must boot Windows XP (at least), not Vista or any other version of Windows.

Windows must be able to coexist with Mac OS X and each system may
not interfere with the operation of the other (basically a traditional
dual boot system where one OS is running at a time)

Your method, upon starting the computer, must offer the user to boot either OS X or Windows XP (hint: GRUB / LILO)

Update 03/16/2006: OnMac has now posted the solution and have included a few mirrors to handle all of the traffic. Included is a bootloader and a "how to" guide in zip format.